After 24 Hours of Saltwater Immersion, the Battery Is Reinstalled into the TIGGO 9 CSH for the Next Underbody Scraping Challenge

Constanța, Romania, 23 September 2026 — After 24 hours submerged in a 3.5% NaCl saltwater solution, the high-voltage battery of the TIGGO 9 CSH was carefully lifted from the test tank on the Black Sea coast today and handed over to CHERY and FEV engineers for inspection.

The inspection found no visible signs of corrosion, swelling or leakage, while no traces of water were detected inside the high- or low-voltage connectors. Following the immersion, the battery recorded a leakage rate of 8.067 Pa/min, while its insulation resistance remained above 500 MΩ.

Once the battery had been reinstalled, the TIGGO 9 CSH moved directly into the second challenge: an underbody scraping test at 14–15 km/h. The vehicle was driven over a 250 mm-high step, deliberately bringing the underbody into direct contact with a rigid obstacle.

From Saltwater Immersion to Battery Reinstallation

The first challenge was designed to determine whether the battery could remain safe and fully functional after 24 hours of saltwater immersion.

The 34.46 kWh high-voltage battery had been fully submerged for 24 hours. Once retrieved, engineers inspected the battery housing, connectors and pressure relief valve.

Under testing conducted by engineers from FEV, a German engineering and technology organisation, and witnessed by more than 150 journalists from 16 European countries, the battery showed no visible corrosion, swelling or leakage. No traces of water were found inside the high- and low-voltage connectors or the pressure relief valve.

Subsequent measurements provided further evidence of the battery's condition after immersion. The tests focused on two key aspects: whether the battery housing had maintained its sealing integrity, and whether the high-voltage electrical system remained safely isolated from the housing.

By pressurising the battery housing and monitoring the rate of pressure loss, engineers assessed the integrity of the battery enclosure. The measured leakage rate was 8.067 Pa/min, significantly below the pass criterion of 31 Pa/min, demonstrating that the battery maintained a high level of sealing integrity after 24 hours of saltwater immersion.

Engineers also measured the electrical resistance between the high-voltage terminals and the housing. With the insulation resistance remaining above 500 MΩ, the results demonstrated that the high-voltage system maintained strong electrical isolation from the battery housing.

（Airtightness test passed）

From Reinstallation to Underbody Scraping

The battery was then reinstalled into the TIGGO 9 CSH. With the battery back in place and the vehicle operating normally, the test moved from prolonged water exposure to physical impact.

（The successful completion of the water immersion test)

The TIGGO 9 CSH was driven over a step-type obstacle at 14–15 km/h, deliberately bringing the vehicle underbody into contact with the test surface. Engineers subsequently inspected the underbody protection system and battery housing to determine whether the impact had caused structural damage, leakage or any abnormal vehicle warning.

The inspection found damage to the PVC coating of the underbody shield, but no structural damage or cracks were found on the battery housing. The high- and low-voltage connectors between the battery pack and the vehicle, as well as the coolant inlet and outlet circuits, showed no signs of scraping or damage.

There was no electrolyte leakage, no abnormal thermal runaway event, and no warning signal on the vehicle dashboard.

The result demonstrated the protective role of the battery's multi-layer structure, which incorporates a 780 MPa steel underbody shield. This high-strength steel is designed to withstand scraping and impacts from rough road surfaces, helping resist deformation caused by stones, uneven surfaces and other obstacles, thereby protecting the battery housing and its internal components.

（The TIGGO 9 drives through the underbody scraping test setup）

A Safety System Designed for Multiple Operating Conditions

The two challenges demonstrated two different demands that a hybrid vehicle battery system may face: prolonged water exposure and physical impact from underneath the vehicle.

Through immersion, inspection, measurement, reinstallation, vehicle operation and underbody testing, the two back-to-back safety challenges examined the battery system at both the component and complete-vehicle levels.

The safety architecture extends beyond physical protection. The CSH Dedicated Hybrid Battery also features a 2 ms high-voltage power cut-off function, designed to rapidly isolate battery power in the event of a collision. Its battery cells are also designed to operate across a temperature range from -35°C to 60°C.

Developed through more than two decades and multiple generations of hybrid technology, CSH has been validated across nine global regions and 44 key countries, covering a wide range of complex driving environments.

The Black Sea Safety Challenge brings this broader engineering approach to Europe, using dedicated test conditions to examine how CHERY's battery protection technologies perform under different forms of stress.

For CHERY, protecting every family on every journey remains a top priority. That is why CHERY continues to put its technology to the test across the world, from extreme cold and heat to high humidity and dry environments. By confronting demanding conditions and examining the results, CHERY continues to challenge, refine and strengthen its technology — with every test bringing the brand closer to its commitment to Safety. For Family.